Electron gun assembling machine



J. L. KRANER ELECTRON GUN ASSEMBLING MACHINE Filed Sept. 10, 1964 2 Sheets-Sheet 1 s V 3 5o i 39 i 38 J 35 63 High Pressur 2 f I Air Supply 69 f, Li

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5 4 INVENTOR.

JQmQsL/ rcZnQF United States Patent 3,297,854 ELECTRON GUN ASSEMBLING MACHINE James L. Kraner, Harwood Heights, 111., assignor to The Rauland Corporation, Chicago, 11]., a corporation of Illinois- Filed Sept. 10, 1964, Ser. No. 394,890 14 Claims. (Cl. 21978) The present invention is directed to a machine for use in the assembling of electron guns. While of general application, it is most particularly adapted for use in the fabrication of cathode-ray tubes or any other type of electron discharge device that develops a beam of electrons. For convenience, it will be described in connection with the production of cathode-ray tubes.

The electron gun of the cathode-ray tube has elements for the generation and focusing of a beam of electrons that is accelerated to an image screen. The portion of the gun which includes the cathode and first grid requires particular care in its manufacture. Generally, the grid is in the form of a cylinder opened at one end and closed at the other although the closure of such other end is centrally apertured to permit the passage of electrons. The cathode is, likewise, cylindrical in form, being small enough to be mounted coaxially within the grid cylinder and it is necessary to maintain a precisely controlled spacing between the apertured closure of the grid cylinder and the closed end of the cathode cylinder which bears the electron emitting material. The other end of the cathode cylinder is open to receive the usual heater of an indirectly heated emitter.

In fabricating this subassembly of the electron gun, it has become the practice to have the cathode cylinder project through a central aperture of an insulating washer and these parts are firmly connected to one another mechanically. The outer dimension of the washer is very close to the internal dimension of the grid cylinder and some spacing provision is made in the grid cylinder against which the insulating washer may rest in order to establish the desired spacing between the grid aperture and the emitting surface of the cathode. This may be accomplished by beading or otherwise deforming the grid cylinder or by using an insert positioned within the grid cylinder ahead of the cathode insulating spacer, dimensioned to establish the required grid-cathode separation and suitably shaped to support the cathode spacer. Whatever mechanism is adopted to position the cathode within the grid cylinder with the desired spacing, it is necessary to secure their spacing and this is usually done by means of a C-shaped retaining ring resting on top of the cathode spacer and welded, at three points about its periphery, to the grid cylinder. In the past, the welding has been performed manually through suitable jigs by which a pressure is applied to the cathode cylinder in order to precisely establish the grid to cathode spacing while the retaining ring is welded at one spot to the grid cylinder. Thereafter, the subassembly is rotated and the procedure repeated at another point and finally a third weld is made in the samemanner. Although this has permitted the subassembly to be manufactured, the shrinkage is unnecessarily high and the subassembly fails to have the uniformity that is greatly desired. Moreover, it is a laborious process that is both costly and time consuming.

Accordingly, it is an object of the invention to provide an improved machine for use in the assembling of components of an electron gun that may be used, for example, in a cathode-ray tube.

It is a particular object of the invention to provide a new and improved machine for assembling the cathodegrid subassembly of a cathode-ray tube.

It is still a further particular object of the invention to provide a novel machine to facilitate fabricating the cathode grid assemblies of the three electron guns comprising the gun assembly of a color cathode-ray tube.

The machine, constructed in accordance with the invention, is useful for assembling the electron gun components of a cathode-ray tube whether it be of the monochrome or color variety. It is most particularly directed to assembling those components which include a grid cylinder having a spacer at one end, a cathode cylinder extending centrally through and secured to an insulating spacer, and a conductive retaining ring having a diameter approximately equal to the internal diameter of the grid cylinder. The machine comprises a workholder for supporting these components in nested concentric relation with the cathode spacer resting against the grid spacer and with the retainer ring resting against the cathode spacer. A primary welding electrode .is movably supported above the workholder. It has an external diameter approximately equal to the internal diameter of the grid cylinder and has a centnal recess with a diameter greater than that of the cathode cylinder. There are means for lowering the primary electrode into a welding position with the cathode cylinder received within its recess and with the primary electrode bearing against the retaining ring to maintain the grid and cathode components under a predetermined clamping pressure. A plurality of secondary electrodes are angularly disposed about the workholder and are individually movable from a rest position spaced from the workholder to a welding position in which the secondary electrode contacts the grid cylinder at a point adjacent the retaining ring. There are means for displacing the secondary electrodes between their rest and welding positions and further means for supplying current to the electrodes to weld the retaining ring to the grid cylinder while the components being assembled are retained under the clamping pressure established by the primary electrodes.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings, in the several figures of which like reference numerals identify like elements, and in which:

FIGURE 1 is an elevational view, partly in section, of one embodiment of the invention especially useful for making the cathode-grid subassemblies of the three guns included in the gun assembly of a three-color cathode-ray tube;

FIGURE 2 is an enlarged view taken along line 2-2 of FIGURE 1 to illustrate the arrangement of secondary welding electrodes;

FIGURE 3 is an enlarged cross-sectional view through the gun assembly and workholder of the machine of FIGURE 1;

FIGURE 4 is a view taken along line 4-4 of FIGURE 3; and

FIGURE 5 represents a further modification of a machine embodying the present invention.

Before describing the machine under consideration, which is generally referred to as a cathode insertion machine, it is appropriate to discuss the subassembly which such a machine fabricates. For this purpose, reference is made to FIGURE 3.

The gun assembly of a three-color cathode-ray tube as currently made comprises three electron guns, two of which appear in FIGURE 3 and are designated 10a and 19b. The guns are positioned at the apices of an equilateral triangle and are arranged with their axes slightly converged toward one another. Their electrode systems are identical and include a grid cylinder 11 at one end which is followed by further cylindrical grids or electrodes 12, 13 and 14 for focusing a beam of electrons originating at a cathode disposed within grid 11. The cylindrical grids mention-ed, with the exception of the cathode, have tabs embedded in insulating support pillars 15, there being three such pillars, and the electrodes of each gun are connected with two of them. This forms a subassembly of the three guns in which the cylindrical grids of each gun are coaxial. Since the machine in question is concerned only with completing the further subassembly of the grid and cathode, no further discussion is required of the electron guns.

The cathode-grid assembly of each gun, of course, includes grid cylinder 11 which is open at one-end and closed at the other but its closed end has a centrally located aperture 16 for admitting electrons emanating from the cathode. Disposed within grid cylinder 11, and resting against its closed end, is a spacer 17 having the form of a cap with a central opening at the end resting against the closure of grid cylinder 11. The opening of cap 17 is coaxial with but much larger than grid aperture 16. The land or flat portion of spacer 17 provides for the cathode a support which is at a precisely controlled distance from grid aperture 16. While it is convenient to use a conductive spacer 17 which is inserted within the grid cylinder, this is not essential. The provision for spacing the cathode may take the form of shaping or heading of the grid cylinder itself.

The cathode is of the indirectly heated type and comprises a cylinder 19 extending centrally through and secured to an insulating spacer 20. Cathode cylinder 19 has a much smaller diameter than grid cylinder 11 but a larger diameter than grid aperture 16 and it bears a coating of emissive material on its closed end which faces the grid aperture. The diameter of cathode spacer 20 is just slightly less than the internal diameter of grid cylinder 11. One end of the cathode cylinder is open to receive a heater (not shown). The final component of the subassembly is a conductive C-shaped retaining ring 21 having a fiat or base portion for resting against cathode spacer 2t and having a flange which is disposed normally to the base of the retaining ring and which has an external diameter approximately equal to or only slightly less than the internal diameter of grid cylinder 11. invention to complete a subassembly of these component parts.

The machine comprises a workholder for supporting these components in nested concentric relation with cathode spacer 29 resting against grid spacer 17 and with retaining ring 21 resting against the cathode spacer. For reasons to be made clear hereafter, it is desirable that the workholder support these components for a limited displacement transversely of the axis of the electron gun and the axis of the workholder supporting that gun. A convenient form of workholder is a guide pin 25 (FIG- URE 3) having a diameter that is smaller than the gun which it is to support. More particularly, the pin diameter is less than the internaldiameter of the cylindrical electrodes 13, 14 of the gun so that the pin may be inserted into these electrodes allowing some freedom of transverse displacement to the gun assembly. Since the machine operates upon the gun assembly of a color cathode-ray tube, there are three such pins, one for each of the guns. These pins are received within apertures of a table 26 rotatably supported by bearings 27 from a stationary portion 28 of the machine in order that the table may be indexed to present each of the three pins and the components supported thereby seri-atim to a welding station. The coupling of any pin to the table is by means of a slot 29 milled in each pin to receive a key 30 projecting from the table into the channelway that accommodates the pin. Each .pin terminates in a handle 31 which permits rotation of the pin so that it may be retracted to a loading position and may thereafter be ele- It is the ultimate function of the machine of this tionary part 24 of the machine.

'of the electrode couples through an air cylinder 39 to I 4 vated and locked in the position of FIGURE 3 wherein it supports an electron gun for the welding operation. Table 26 has a pinion 23 formed about its central section as a means for mechanic-ally coupling the table to an index type of drive.

A primary welding electrode is movably supported above the workholder. Where the machine operates upon an assembly of three guns as in the case of a color cathode-ray tube, the welding electrode is movably supported above the workholder instantaneously positioned in the welding station. As shown in FIGURE 3, the primary electrode 35 has an external diameter approximately equal to the internal diameter of the grid cylinder; more specifically, the external diameter of electrode 35 is just slightly less than the internal diameter of the flange of retaining ring 21. The electrode has a central recess 36, the diameter of which exceeds the external diameter of cathode cylinder 19.

As shown in FIGURE 1, electrode 35 extends through an insulating bushing 37, electrically isolating the electrode from a carriage 38 movably supported from a sta- The upper extremity a machine bolt 40 or other mechanical device for connecting the electrode to carriage 38 for movement therewith between a rest position and a welding position. Carriage 38 is connected through an adjustable coupling 41 to another air cylinder 42, this latter air cylinder constituting means for lowering electrode 35 into a welding position (FIGURE 3) relative to the electron gun instantaneously at the welding station.

Lowering or elevating of carriage 38 through air cylinder 42 is under the control of high pressure air that may be admitted through lines 43, 44 to opposite sides of the .piston included within the cylinder. The cylinder is supported from the stationary frame of the machine and a bushing 45 provides support and guidance for carriage :38. A stop 46 threaded upon a threaded portion of the coupling between carriage 38 and cylinder 42 permits adjustment of the descent of the carriage by its engagement with bushing 45.

Bushing 45 serves as the support for a pair of micro- Iswitches 50 and 51, the functions of which will be considered presently. Actuation of switch 50 is under the control of an actuator 52 of adjustable effective length carried by the coupler which extends between cylinder 42 A similarly adjustable actuator 53 and carriage 38. traveling with carriage 38 is provided for actuating switch 51.

When welding electrode 35 has been displaced to its welding position by carriage 38, cathode cylinder 19 is received within its recess 36 and electrode 35 bears against the flat or base portion of retaining ring 21 to maintain the components of the cathode-grid subassemblyiunder a predetermined clamping pressure and it is desirable that this pressure be maintained uniform. That is accomplished by air cylinder 39 which connects with a high pressure line 54, and a conventional pressure regulator (not shown) within that line maintains a fixed pressure exerted against electrode 35 and the cathode-grid components during the entire welding operation.

There are a plurality of secondary electrodes angularly disposed about the workholder for cooperation with primary electrode 35 to make the necessary Welds. It is preferred that there be three welds and, therefore, as shown in FIGURE 2, the machine has three secondary electrodeassemblies 60 spaced apart about the axis of primary electrode 35. Each electrode assembly is movable from a rest position spaced from the workholder to ,a welding position in which the secondary electrode contacts grid cylinder 11 of the gun in the welding station, engaging it at a' point adjacent the flange of retaining 7 ring 21. The showing of FIGURE 4 represents two of the j secondary electrodes 63 in their rest positions and athird electrode 63' in its welding position, contacting the outer periphery of grid cylinder 11.

Each secondary electrode assembly 60 has a pivoted lever 61 supported from the frame of the assembly which, in turn, is secured to movable carriage 38. The coupling of lever 61 to the assembly is through an insulating bushing 62 which isolates the electrode itself from its supports. The secondary electrode element 63 is removably secured to the free end of lever 61 which is adjacent primary electrode 35 and the electrode is displaceable between its rest and welding positions by pivoting lever 61 about its coupling in assembly 60.

The means for displacing the secondary electrodes comprises a further series of air cylinders 65, one for each secondary electrode assembly although only one is shown in the drawings. As shown in FIGURE 1, the piston of air cylinder 65 connects through a rod 66 to pivoted lever 61. Their coupling is through a pin and slot. Each such cylinder has high pressure lines 67, 68 for controlling displacement of the secondary electrodes.

There are means for supplying current to the machine electrodes to weld retaining ring 21 to grid cylinder 11 while the cathode-grid components are retained under clamping pressure by primary electrode 35. As shown, this means includes a cable 69 connecting to primary electrode 35 and a cable 70 connecting to secondary electrode 63. Since there are three secondaries which are to be excited in sequence rather than simultaneously, there are three leads 70 although only one appears in FIG- URE 1.

It is desirable to program the operation of the machine and to have interlocks that guard against machine failures. The programming is accomplished by means of a control system 75 shown in block form in FIGURE 1 since it is formed of well-known conventional units and, of itself, constitutes no novelty. For convenience, the high pressure lines are shown as connecting to a high pressure supply 76 through the control system and the cables 69, 70 connect to a DC. power supply which is also included within control system 75 and energized from an AC. supply through lead-in 77.

The control system 75, in addition to housing the D.C. supply for the welding electrodes, has three electrically energized timers. Each timer controls the process by which primary electrode 35 and one secondary electrode 63 makes on weld of retainer 21 to grid cylinder 11. The final function of any such timer is to initiate the next succeeding timer to the end that secondary electrodes 63 are moved in a timed sequence from their rest to their welding positions so that only one secondary electrode 63 assumes its welding position at a time, until the third and final timer as been initiated. The last function of the No. 3 timer is to initiate an index mechanism presently to be described. Control system 75 further has a manually operated starting switch which, when energized, operates a valve to admit air through line 43 to cylinder 42 and lower primary electrode 35-.

Where, for the embodiment under consideration, the machine is to weld three guns of an assembly, it is necessary to index table 26 so that after a welding cycle has been completed with respect to one gun, the table may be indexed to bring the next gun of the family into the Welding station. The indexing arrangement includes a motor 80 coupled through a slip clutch 81 to a chain drive 82 which connects with pinion 31 of table 26. The remainder of the means for indexing this table includes an air cylinder 83 and its controls. The piston of this cylinder connects with a cam disk 84 by means of a shot pin 85 which may be received in any of a number of indexing apertures provided in disk 84. High pressure lines 86 of cylinder 83 are also returned to the control system so that the piston may be displaced and the indexing accomplished in timed relation not only to the welding cycle carried out by the machine but also the returning of primary electrode 35 from its welding to its rest position. Included in the control of the indexing is microswitch 51 which may be actuated upon the return stroke of carriage 38 so that through control system 75 the high pressure air supply may be admitted to cylinder 83 and permit indexing to take place.

Associated with the indexing mechanism are a further pair of microswitches collectively designated 87 and concurrently actuated by a switch operator 88 which travels with shot pin 85. Another switch 89 is subject to actuation by the same switch operator to control a timer included in control system 75 and determining the return movement of shot pin 85.

It may sometimes happen that a secondary electrode may fail to return to its rest position upon the completion of a weld. This could result in damage to the gun assembly and, therefore, a protective interlock 90 is provided. It is subject to actuation by a switch operator 92 moving with the piston of air cylinder 65. Of course, there is a microswitch and operator of this type provided for each of the three secondary electrodes. The microswitches may be connected in series in the control that determines the elevation of carriage 38, preventing the carriage from rising unless all three microswitches are set to indicate that each of the secondary electrodes is in its rest position. Alternatively, any such microswitch may be connected through the control system 75 to the end that the sequential operation of the secondary electrodes, bringing them from their rest to their welding positions, is interrupted if any such electrode fails to return to its rest position after having participated in the welding of retainer 21 to grid cylinder 11.

Finally, there is a shutoif switch 95 to be operated by cam plate 84 and shut off the machine after the welds for a complete gun assembly have been made.

In describing the operation of the machine, it will be assumed initially that carriage 38 is in its uppermost position, holding electrode 35 away from the welding station. Manipulation of handles 31 permits all three guide pins 25 to recede into table 26 which is now ready for loading. A three-gun assembly of the type described above is placed in position with each gun in axial alignment with the recess of table 26 accommodating one of the guide pins. The pins are elevated and locked into position holding each gun appropriately for welding and yet permitting a limited displacement of any gun in the welding station during the welding operation. Loading of the machine has now taken place and the operator actuates the manual start switch.

At this time, control system 75 actuates the valve supplying high pressure air to cylinder 42 to displace its piston and lower carriage 38, and along with it electrode 35 to the welding position. As electrode 35 assumes its welding position (FIGURE 3) cathode cylinder 19 enters recess 36 of the electrode and the electrode itself firmly engages the base of retaining ring 21. The outer wall of electrode 35 is very close to the inner wall of the flange of the retaining ring. In the descent of electrode 35, the electrode homes against the assembled components before the final movement of carriage 38 has been arrested by stop 46. This is permitted by the piston of air cylinder 39 which recedes within that cylinder and the air line 54 supplying air thereto puts the assembled components under pressure. A regulating valve included in that line causes the pressure to be maintained constant throughout the entire time that electrode 35 is in the welding station. The pressure in one constructed embodiment of the machine is approximately 3 pounds.

In the downward movement of carriage 38, operator 52 actuates microswitch 50 and energizes timer No. 1 of control system 75, this being the timer that controls a particular one of secondary electrodes ates a valve controlling the supply of high pressure air to line 67 leading to cylinder 65 the piston of which decends and displaces lever 61 carrying the particular secondary electrode 63 controlled by the timer in question.

63. The timer actu- The air pressure causes a mechanical pressure to build up between primary electrode 35 and the secondary electrode 63 that has been moved into the welding position. Since the gun has limited transverse movement and since its retaining ring 21 is discontinuous, the parts to be welded are firmly clamped between the electrodes and when the pressure attains a predetermined level, an illustrative figure is 15 pounds, the DC. supply of control system 75 is actuated and the welding electrodes are excited. This is accomplished by having the welding circuit triggered by a pressure sensitive switch (not shown) which responds to the pressure that builds in line 67. As a consequence welding current flows and a spot weld is formed between retaining ring 21 and grid cylinder 11. The timer now causes air to be admitted through line 68 to the other side of the piston in air cylinder 65, elevating the piston and returning secondary electrode 63 to its rest position. Immediately thereafter, timer No. 1 will have completed its cycle and as it shuts off, it energizes timer No. 2 controlling another of the secondary electrodes 63.

The same welding operation is now performed but through the agency of primary electrode 35 and a second one of electrodes 63. This produces another weld of retaining ring 21 to grid cylinder 11 spaced 120 from the first such weld. As timer No. 2completes its program, timer No. 3 is energized.

The same sequence follows the operation of timer No. 3 and a third weld is made. At this juncture, the cathodegrid subassembly has been completed and throughout the entire welding process the components of the assembly have been maintained under a uniform clamping pressure by primary electrode 35.

As timer No. 3 finishes its program, it causes the control system to admit air through line 44 into cylinder 42 as required to elevate carriage 38. In other Words, at the completion of one Welding cycle in which a cathode-grid vates and restores primaryelectrode 35 to its rest position.

As carriage 38 is returned, microswitch 51 is operated by actuator 53 to initiate the index cycle. At the start of this cycle, control system 75 admits air to cylinder 83, retracting shot pin 85 from an aperture of cam plate 84. As the shot pin withdraws, both microswitches 87 operate. The first of these energizes index motor 80; the other is an interlock which opens the control circuits to prevent carriage 38 from descending. In the final travel of shot pin 85, operator 88 actuates microswitch 89 which controls the index timer.

Motor 80 now star-ts the rotation of table 26. Shortly after table rotation has started, but delayed sufiiciently to have the aperture previously engaged by shot pin 85 moved clear from the path of travel of the pin, the timer runs out causing air to be admitted through the other line to air cylinder 83 and elevate pin 85. As the next indexed position is approached, pin 85 is able to enter an aperture of cam plate 84 and to resist further rotation of table 26. At this time, the index will have been completed and both microswitches 87 will have been actuated again. One of them de-energizes motor 80 and the other completes the control circuit for displacement of carriage 38 initiating a second welding cycle after the table indexing has been accomplished. In other words, this second microswitch of pair 87 starts the descent of carriage 38 to repeat the welding cycle that has been described.

Obviously, the indexing of table 26 brings another gun of the assembly into the welding station so that in the welding cycle that is now initiated, its cathode-grid subassembly is completed. Thereafter, there is a further indexing of table 26 to present the third gun to the welding station and its cathode-grid subassembly is completed. Following that, the table is indexed once more, returning it to its starting position. In this final step of the index cycle, cam plate 84 actuates switch 95 and turns the subassembly shall have been completed, carriage 38 elemachine off. At the time switch actuates, carriage 38 will have been in its uppermost position carrying welding electrode 35 to its rest position. Manipulation of handles 31 permits guide pins 25 to recede and the finished gun assembly may be lifted from table 26. The operator may now reload the machine and process another three-gun assembly.

As shown in FIGURE 1, it is convenient to place a housing over the major portion of the machine, leaving exposed the work table and the necessary portions of the welding electrodes.

The machine of FIGURE 1 accommodates but a single gun assembly at one time because it has but a single workholder. If the number of workholders is increased and means are provided to index the workholders as such into the vicinity of the welding electrodes, an operator may be loading the machine while a welding operation is taking place. This feature is shown in the embodiment of FIGURE 5 which is addressed to the assembling of single gun devices for monochrome tubes as distinguished from the three-gun assemblies of color tubes processed by the machine of FIGURE 1. For the most part, the machine of FIGURE 5 is similar to that previously described, distinguishing principally in the arrangement for displacing the secondary electrodes and in the use of a plurality of discrete workholders. In this case, for-example, each secondary electrode assembly 60 is mounted in a horizontal plane from carriage 38. Its electrode element 63 is movable in a horizontal plane from its rest to its weld position. This is accomplished by a slotted coupling 101 between the electrode housing and rod 66 which connects with the piston of air cylinder 65.

Moreover, a series of workholders 105 are angularly spaced about table 26. Each of these has but a single pin 25 for supporting a single electron gun assembly. It will be observed from FIGURE 5 that each gun assembly has one series of grids and a pair of insulating pillars which maintain the various grids in coaxial alignment.

In the operation of the machine of FIGURE 5, a complete Welding cycle causes the cathode-grid assembly of the gun instantaneously at the welding station to be completed. After that cycle has run its course and the indexing mechanism is energized, the rotation of table 26 brings the next succeeding workholder into the welding station for a similar operation.

In constructed embodiments of the described machine, it has been determined that the cathode-grid subassemblies have a remarkable uniformity and the yield is much greater than previously possible in the manual welding of these subassemblies. A very high production rate is obtained and the welds have a high degree of uniformity.

While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from theinvention in its broader aspects, and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.

I claim:

1. A machine for assembling electron gun components of a cathode-ray tube including a grid cylinder having a spacer at one end, a cathode cylinder extending centrally through and secured to an insulating spacer, and a conductive retaining ring having a diameter approximately equal to the internal diameter of said grid cylinder, said machine comprising:

a workholder for supporting said components in nested concentric relation with said cathode spacer resting against said grid spacer and said retaining ring resting against said cathode spacer;

a primary welding electrode movably supported above said workholder, having an external diameter approximately equal to the internal diameter of said grid cylinder and having a central recess with a diameter greater than that of said cathode cylinder;

means for lowering said primary electrode into a Welding position with said cathode cylinder received within said recess and with said primary electrode bearing against said retaining ring to maintain said components under a predetermined clamping pressure;

a plurality of secondary electrodes angularly disposed about said workholder and individually movable from a rest position spaced from said workholder to a welding position in which said secondary electrode contacts said grid cylinder at a point adjacent said retaining ring;

means for displacing said secondary electrodes between their rest and welding positions;

and means for supplying current to said electrodes to Weld said retaining ring to said grid cylinder While said components are retained under said clamping pressure.

2. A machine for assembling electron gun components of a cathode-ray tube including a grid cylinder having a spacer at one end, a cathode cylinder extending centrally through and secured to an insulating spacer, and a conductive retaining ring having a diameter approximately equal to the internal diameter of said grid cylinder, said machine comprising:

a workholder for supporting said components in nested concentric relation with said cathode spacer resting against said grid spacer and said retaining ring resting against said cathode spacer;

a primary welding electrode movably supported above said workholder, having an external diameter approximately equal to the internal diameter of said grid cylinder and having a central recess with a diameter greater than that of said cathode cylinder;

means for lowering said primary electrode into a welding position with said cathode cylinder received within said recess and with said primary electrode bearing against said retaining ring to maintain said components under a predetermined clamping pressure;

a plurality of secondary electrodes angularly disposed about said workholder and individually movable from a rest position spaced from said workholder to a weld ing position in which said secondary electrode contacts said grid cylinder at a point adjacent said retaining ring;

means for displacing said secondary electrodes between their rest and welding positions in a timed sequence so that only one of said secondary electrodes assumes its aforesaid welding position at a time;

and means for supplying current to said primary electrode and to the one of said secondary electrodes instantaneously in its aforesaid welding position to Weld said retaining ring to said grid cylinder while said components are retained under said clamping pressure.

3. A machine for assembling electron gun components of a cathode-ray tube including a grid cylinder having a spacer at one end, a cathode cylinder extending centrally through and secured to an insulating spacer, and aconductive retaining ring having a diameter approximately equal to the internal diameter of said grid cylinder, said machine comprising:

a workholder for supporting said components for limited displacement transversely of the axis of said workholder and in nested concentric relation with said cathode spacer resting against said grid spacer and said retaining ring resting against said cathode spacer;

a primary welding electrode movably supported above said workholder, having an external diameter approximately equal to the internal diameter of said grid cylinder and having a central recess with a diameter greater than that of said cathode cylinder;

means for lowering said primary electrode into a welding position with said cathode cylinder received within said recess and with said primary electrode bearing against said retaining ring to maintain said components under a predetermined clamping pressure;

a plurality of secondary electrodes angularly disposed about said workholder and individually movable from a rest position spaced from said workholder to a welding position in which said secondary electrode contacts said grid cylinder at a point adjacent said retaining ring;

means for displacing said secondary electrodes between their rest and welding positions in a timed sequence so that only one of said secondary electrodes assumes aforesaid welding position at a time;

and means for supplying current to said primary electrode and to the one of said secondary electrodes instantaneously in its aforesaid welding position to Weld said retaining ring to said grid cylinder while said components are retained under said clamping pressure.

4. A machine for assembling into the electron gun of a cathode-ray tube certain components including a grid cylinder having a spacer at one end, a cathode cylinder extending centrally through and secured to an insulating spacer, and a conductive retaining ring having a diameter approximately equal to the internal diameter of said grid cylinder, said machine comprising:

a workholder comprising a guide pin having a diameter smaller than that of said gun for insertion into said gun to support said components for limited displacement transversely of the axis of said guide pin and in nested concentric relation with said cathode spacer resting against said grid spacer and said retaining ring resting against said cathode spacer;

a primary welding electrode movably supported above said workholder, having an external diameter approximately equal to the internal diameter of said grid cylinder and having a central recess with a diameter greater than that of said cathode cylinder;

means for lowering said primary electrode into a welding position with said cathode cylinder received within said recess and with said primary electrode bearing against said retaining ring to maintain said components under a predetermined clamping pressure;

a plurality of secondary electrodes angularly disposed about said workholder and individually movable from a rest position spaced from said workholder to a Welding position in which said secondary electrode contacts said grid cylinder at a point adjacent said retaining ring;

means for displacing said secondary electrodes between their rest and welding positions in a timed sequence so that only one of said secondary electrodes assumes its aforesaid welding position at a time;

and means for supplying current to said primary electrode and to the one of said secondary electrodes instantaneously in its aforesaid welding position to weld said retaining ring to said grid cylinder while said components are retained under said clamping pressure.

5. A machine for assembling into each of the three electron guns of the gun assembly of a color cathode-ray tube certain components including a grid cylinder having a spacer at one end, a cathode cylinder extending centrally through and secured to an insulating spacer, and a conductive retaining ring having a diameter approximately equal to the internal diameter of said grid cylinder, said machine comprising:

a workholder comprising a table supporting three guide pins individually having a diameter smaller than that of said guns for insertion into an assigned one of said guns to support said components for limited displacement transversely of the axis of said guide pin and in nested concentric relation with said cathode spacer resting against said grid spacer and said retaining ring resting against said cathode spacer,

said table being indexable to present said pins and the components supported thereby seriatim to a welding station;

a primary welding electrode movably supported at said welding station above said workholder, having an external diameter approximately equal to the internal diameter of said grid cylinder and having a central recess with a diameter greater than that of said cathode cylinder;

means for lowering said primary electrode into a welding position relative to the electron gun instantaneously at said welding station with said cathode cylinder received within said recess and with said primary electrode bearing against said retaining ring to maintain said components under a predetermined clamping pressure;

a plurality of secondary electrodes angularly disposed about said workholder at said welding station and individually movable from a rest position spaced from said workholder to a Welding position in which said secondary electrode contacts said grid cylinder of the gun in said welding station at a point adjacent said retaining ring;

means for displacing said secondary electrodes between their rest and welding positions in a timed sequence so that only one of said secondary electrodes assumes its aforesaid welding position at a time;

means for supplying current to said primary electrode and to the one of said secondary electrodes instantaneously in its aforesaid welding position to weld said retaining ring to said grid cylinder while said components are retained under said clamping pressure;

and means for indexing said table in timed relation to the completion of the welding of said retaining ring to said grid cylinder in each gun of said assembly.

6. A machine for assembling into each of the three electron guns of the gun assembly of a color cathode-ray tube certain components including a grid cylinder having a spacer at one end, a cathode cylinder extending centrally through and secured to an insulating spacer, and a conductive retaining ring having a diameter approximately equal to the internal diameter of said grid cylinder, said machine comprising:

a workholder comprising a table supporting three guide pins individually having a diameter smaller than that of said guns for insertion into an assigned one of said guns to support said components for limited displacement transversely of the axis of said guide pin and in nested concentric relation with said cathode spacer resting against said grid spacer and said retaining ring resting against said cathode spacer, said table being indexable to present said pins and the components supported thereby seriatim to a welding station;

a primary Welding electrode movably supported at said welding station above said workholder, having an external diameter approximately equal to the internal diameter of said grid cylinder and having a central recess with a diameter greater than that of said cathode cylinder;

means for lowering said primary electrode at the start of a welding cycle into a Welding position relative to the electron gun instantaneously at said welding station with said cathode cylinder received Within said recess and with said primary electrode bearing against said retaining ring to maintain said components under a predetermined clamping pressure and for returning said primary electrode to its initial position at the completion of a welding cycle;

a plurality of secondary electrodes angularly disposed about said workholder at said welding station and individually movable from a rest position spaced from said workholder to a Welding position in which said secondary electrode contacts said grid cylinder of the gun in said welding station at a point adjacent said retaining ring; 7 means for displacing said secondary electrodes between their rest and welding positions in a timed sequence in each weldin cycle so that only one of said secondary electrodes assumes its aforesaid welding position at a time; means for supplying current to said primary electrode and to the one of said secondary electrodes instantaneously in its aforesaid welding position to weld said retaining ring to said grid cylinder while said components are retained under said clamping pressure; and means for indexing said table in timed relation to the completion of a welding cycle and the returning of said primary electrode to its aforesaid initial position. 7. A machine for assembling into each of the three electron guns of the gun assembly of a color cathode-ray tube certain components including a grid cylinder having a spacer at one end, a cathode cylinder extending centrally through and secured to an insulating spacer, and a conductive retaining ring having a diameter aproximately equal to the internal diameter of said grid cylinder, said machine comprising:

a workholder comprising a table supporting three guide pins individually having a diameter smaller than that of said guns for insertion into an assigned one one of said guns to support said components for limited displacement transversely of the axis of said guide pin and in nested concentric relation with said cathode spacer resting against said grid spacer and said retaining ring resting against said cathode spacer, said table being indexable to present said pins and the components supported thereby seriatim to a welding station;

a primary welding electrode movably supported at said welding station above said workholder, having an external diameter approximately equal to the internal diameter of said grid cylinder and having a central recess with a diameter greater than that of said cathode cylinder;

means for lowering said primary electrode at the start of a Welding cycle into a welding position relative to the electron gun instantaneously at said welding st-ation with said cathode cylinder received within said recess and with said primary electrode bearing against said retaining ring to maintain said components under a predetermined clamping pressure and for returning 7 said primary electrode to its initial position at the completion of a Welding cycle;

a plurality of secondary electrodes angularly disposed about said workholder at said welding station and individually movable from a rest position spaced from said work-holder to a Welding position in which said secondary electrode contacts said grid cylinder of the gun in said welding station at a point adjacent said retaining ring;

means for displacing said secondary electrodes between their rest and welding positions in a timed sequence in each welding cycle so that only one of said secondary electrodes assumes its aforesaid welding position at a time;

means for supplying current to said primary electrode and to the one of said secondary electrodes instantaneously 'in its aforesaid welding position to weld said retaining ring to said grid cylinder While said components are retained under said clamping pressure;

and means for indexing said table in timed relation to the completion of a welding cycle and the returning of said primary electrode to its aforesaid initial position and for initiating another welding cycle after machine comprising:

a workholder for supporting said components in nested concentric relation with said cathode spacer resting against said grid spacer and said retaining ring resting against said cathode spacer;

a primary welding electrode movably supported above said workholder, having an external diameter approximately equal to the internal diameter of said rid cylinder and having a central recess with a diameter greater than that of said cathode cylinder;

means for lowering said primary electrode into a welding position with said cathode cylinder received within said recess and with said primary electrode bearing against said retaining ring to maintain said components under a predetermined clamping pressure;

a plurality of secondary electrodes angularly disposed about said workholder and individually movable from a rest position spaced from said workholder to a welding position in which said secondary electrode contacts said grid cylinder at a point adjacent said retaining ring;

means for displacing said secondary electrodes between their rest and welding positions in a timed sequence so that only one of said secondary electrodes assumes its aforesaid welding position at a time;

means for supplying current to said primary electrode and to the one of said secondary electrodes instantaneously in its aforesaid welding position to weld said retaining ring to said grid cylinder while said components are retained under said clamping pressure;

and means for interrupting the sequential displacement of said secondary electrodes in the event that any of said secondary electrodes fails to return to its aforesaid rest position after the making of a Weld.

.9. A machine for assembling electron gun components of a cathode-ray tube including a grid cylinder having a spacer at one end, a cathode cylinder extending centrally through and secured to an insulating spacer, and a conductive retaining ring having a diameter approximately equal to the internal diameter of said grid cylinder, said machine comprising:

a workholder for supporting said components in nested concentric relation with said cathode spacer resting against said grid spacer and said retaining ring resting against said cathode spacer;

a primary welding electrode movably supported above said workholder, having an external diameter approximately equal to the internal diameter of said grid cylinder and having a central recess with a diameter greater than that of said cathode cylinder;

means for lowering said primary electrode into a welding position with said cathode cylinder received within said recess and with said primary electrode bearing against said retaining ring to maintain said components under a predetermined clamping pressure;

a plurality of secondary electrodes angularly disposed about said workholder and individually movable from a rest position spaced from said workholder to a welding position in which said secondary electrode contacts said grid cylinder at a point adjacent said retaining ring;

means for displacing said secondary electrodes between their rest and welding positions;

and means, responsive to a predetermined pressure between said primary electrode and one of said secondary electrodes, for supplying current to said electrodes to weld said retaining ring to said grid cylinder While components are retained under said clamping pressure.

10. A machine for assembling electron gun components of a cathode-ray tube including a grid cylinder having a spacer at one end, a cathode cylinder extending centrally through and secured to an insulating spacer, and a conductive retaining ring having a diameter approximately equal to the internal diameter of said grid cylinder, said machine comprising: v I

a workholder for supporting said components in nested concentric relation with said cathode spacer resting against said grid spacer and said retaining ring resting against said cathode spacer;

a primary Welding electrode movably supported above said workholder, having an external diameter approximately equal to the internal diameter of said grid cylinder and having a central recess with a diameter greater than that of said cathode cylinder;

means for lowering said primary electrode into a welding position with said cathode cylinder received within said recess and with said primary electrode bearing against said retaining ring to maintain said components under a predetermined clamping pressure;

a plurality of secondary electrodes angularly disposed about said workholder and individually movable from a rest position spaced from said workholder to a welding position in which said secondary electrode contacts said grid cylinder at a point adjacent said retaining ring;

means, responsive to the lowering of said primary electrode into a Welding position, for displacing said secondary electrodes between their rest and welding positions in a timed sequence so that only one of said secondary electrodes assumes its aforesaid Welding position at a time;

and means for supplying current to said primary electrode and to the one of said secondary electrodes instantaneously in its aforesaid welding position to weld said retaining ring to said grid cylinder While said components are retained under said clamping pressure.

11. A machine for assembling electron gun components of a cathode-ray tube including a grid cylinder having a spacer at one end, a cathode cylinder extending centrally through and secured to an insulating spacer, and a conductive retaining ring having a diameter approximately equal to the internal diameter of said grid cylinder, said machine comprising:

a workholder comprising a table having a plurality of devices spaced angularly thereabout for individually supporting said components of a particular electron gun in nested concentric relation with said cathode spacer resting against said grid spacer and said retaining ring resting against said cathode spacer, said table being indexable to present said devices and the components supported thereby seriatim to a welding station;

a primary welding electrode movably suported at said welding station above said workholder, having an external diameter approximately equal to the internal diameter of said grid cylinder and having a central recess with a diameter greater than that of said cathode cylinder;

means for lowering said primary electrode into a weld ing position relative to the electron gun instantaneously at said welding station with said cathode cylinder received Within said recess and with said primary electrode bearing against said retaining ring to maintain said components under a predetermined clamping pressure;

a plurality of secondary electrodes angularly disposed about said workholder at said Welding station and i individually movable from a rest position spaced from said workholder to a welding position in which said secondary electrode contacts said grid cylinder of the gun in said welding station at a point adjacent said retaining ring;

' means for displacing said secondary electrodes between their rest and welding positions in a timed sequence so that only one of said secondary electrodes assumes its aforesaid welding position at a time;

means for supplying current to said primary electrode and to the one of said secondary electrodes instantaneously in its aforesaid welding position to weld said retaining ring to said grid cylinder while said components are retained under said clam-ping pressure;

and means for indexing said table in timed relation to the completion of the welding of said retaining ring to said grid cylinder in each gun of said assembly.

12. A machine for assembling electron gun components of a cathode-ray tube including a grid cylinder having a spacer at one end, a cathode cylinder extending centrally through and secured to an insulating spacer, and a conductive retaining ring having a diameter approximately equal to the internal diameter of said grid cylinder, said machine comprising:

a workholder for supporting said components in nested concentric relation with said cathode spacer resting against said grid spacer and said retaining ring resting against said cathode spacer;

a primary welding electrode movably supported above said workholder, having an external diameter approximately equal to the internal diameter of said grid cylinder and having a central recess with a diameter greater than that of said cathode cylinder;

means for lowering said primary electrode int-o a welding position with said cathode cylinder received within said recess and with said primary electrode bearing against said retaining ring to maintain said components under a predetermined clamping pressure;

a plurality of secondary electrodes angularly disposed about said workholder and individually movable, transversely of the path of movement of said primary electrode, (from a rest position spaced from said workholder to a welding position in which said secondary electrode contacts said grid cylinder at a point adjacent said retaining ring;

means for displacing said secondary electrodes between their rest and welding positions in a timed sequence so that only one of said secondary electrodes assurnes its aforesaid welding position at a time;

and means for supplying current to said primary electrode and to the one of said secondary electrodes instantaneously in its aforesaid welding position to weld said retaining ring to said grid cylinder while said components are retained under said clamping pressure.

13. A machine for assembling electron gun components of a cathode-ray tube including a grid cylinder having a spacer at one end, a cathode cylinder extending centrally through and secured to an insulating spacer, and a conductive C-shaped retaining ring having a flat portion for resting on said cathode spacer, a flange extending normal to said flat portion and an external diameter approximately equal to the internal diameter of said grid cylinder, said machine comprising:

a workholder for supporting said components in nested concentric relation with said cathode spacer resting against said grid spacer and said retaining ring resting against said cathode spacer;

a primary welding electrode mova'bly supported above said workholder, having an external diameter ap- 16 proximately equal to the internal diameter of said flange of said retaining ring and having a central recess with a diameter greater than that of said cathode cylinder;

means for lowering said primary electrode into a welding position with said cathode cylinder received within said recess and with said primary electrode bearing against said flat portion of said retaining ring to maintain said components under a predetermined clamping pressure;

a plurality of secondary electrodes angularly disposed about said workholder and individually movable from a rest position spaced from said workholder to a welding position in which said secondary electrode contacts said grid cylinder at a point adjacent said flange of said retaining ring;

means for displacing said secondary electrodes between their rest and welding positions;

and means for supplying current to said electrodes to weld said retaining ring to said grid cylinder while said components are retained under said clamping pressure.

14. A machine for assembling electron gun components of a cathode-ray tube including a grid cylinder having a spacer at one end, a cathode cylinder extending centrally through and secured to an insulating spacer, and a conductive C-shaped retaining ring having a flat portion for resting on said cathode spacer, a flange extending normal to said flat portion and an external diameter approximately equal to the internal diameter of said grid cylinder, said machine comprising:

a workholder for supporting said components in nested concentric relation with said cathode spacer resting against said grid spacer and said retaining ring restingagainst said cathode spacer;

a primary welding electrode movably supported above said workholder, having an external diameter approximately equal to the internal diameter of said flange of said retaining ring and having a central recess with a diameter greater than that of said cathode cylinder;

means for lowering said primary electrode into a welding position with said cathode cylinder received within said recess and with said primary electrode bearing against said flat portion of said retaining ring to apply a predetermined clamping pressure to said components;

means for maintaining said clamping pressure substantially constant while said primary electrode is in said welding position;

a plurality of secondary electrodes angularly disposed about said workholder and individually movable from a rest position spaced from said workholder to a welding position in which said secondary electrode contacts said grid cylinder at a point adjacent said flange of said retaining ring;

means for displacing said secondary electrodes between their rest and welding positions; 7

and means for supplying current to said electrodes to weld said retaining ring to said grid cylinder while said components are retained under-said clamping pressure.

References Cited by the Examiner UNITED STATES PATENTS 2,179,282 11/1939 Dawson ,219--87 2,559,547 7/1951 Reed 2119- 3,072,778' 1/1963 Cook 2119-78 RICHARD M. woon, Primary Examiner.

B. A. STEIN, Assistant! Examiner. 

1. A MACHINE FOR ASSEMBLING ELECTRON GUN COMPONENTS OF A CATHODE-RAY TUBE INCLUDING A GRID CYLINDER HAVING A SPACER AT ONE END, A CATHODE CYLINDER EXTENDING CENTRALLY THROUGH AND SECURED TO AN INSULATING SPACER, AND A CONDUCTIVE RETAINING RING HAVING A DIAMETER APPROXIMATELY EQUAL TO THE INTERNAL DIAMETER OF SAID GRID CYLINDER, SAID MACHINE COMPRISING: A WORKHOLDER FOR SUPPORTING SAID COMPONENTS IN NESTED CONCENTRIC RELATION WITH SAID CATHODE SPACER RESTING AGAINST SAID GRID SPACER AND SAID RETAINING RING RESTING AGAINST SAID CATHODE SPACER; A PRIMARY WELDING ELECTRODE MOVABLE SUPPORTED ABOVE SAID WORKHOLDER, HAVING AN EXTERNAL DIAMETER APPROXIMATELY EQUAL TO THE INTERNAL DIAMETER OF SAID GRID CYLINDER AND HAVING A CENTRAL RECESS WITH A DIAMETER GREATER THAN THAT OF SAID CATHODE CYLINDER; MEANS FOR LOWERING SAID PRIMARY ELECTRODE INTO A WELDING POSITION WITH SAID CATHODE CYLINDER RECEIVED WITHIN SAID RECESS AND WITH SAID PRIMARY ELECTRODE BEARING AGAINST SAID RETAINING RING TO MAINTAIN SAID COMPONENTS UNDER A PREDETERMINED CLAMPING PRESSURE; A PLURALITY OF SECONDARY ELECTRODES ANGULARLY DISPOSED ABOUT SAID WORKHOLDER AND INDIVIDUALLY MOVABLE FROM A REST POSITION SPACED FROM SAID WORKHOLDER TO A WELDING POSITION IN WHICH SAID SECONDARY ELECTRODE CONTACTS SAID GRID CYLINDER AT A POINT ADJACENT SAID RETAINING RING; MEANS FOR DISPLACING SAID S ECONDARY ELECTRODES BETWEEN THEIR REST AND WELDING POSITIONS; AND MEANS FOR SUPPLYING CURRENT TO SAID ELECTRODES TO WELD SAID RETAINING RING TO SAID GRID CYLINDER WHILE SAID COMPONENTS ARE RETAINED UNDER SAID CLAMPING PRESSURE. 